1. Field of the Invention
The present invention relates generally to the fields of residential and commercial construction. More specifically, the invention pertains to the construction of pre-formed structural walls which may be positioned above or below ground level in a variety of construction applications where increased structural strength for extreme weather conditions and improved resistance to fire, insects, mold, and moisture is desired.
2. Description of the Related Art
For decades, the technology relating to structural walls in residential and commercial construction has seen little progress. The predominant method for constructing the conventional structural walls, foundation walls in particular, has been to pour the concrete footer and to use cinder blocks to build the foundation wall. More recently, a foundation wall molding method has gained acceptance where mold forms are assembled and concrete is poured into a void between the mold forms to create a solid concrete foundation wall.
While both of these construction methods produce structurally sound foundation walls, there are a number of disadvantages associated with using these conventional construction methods. Cinder blocks and concrete are expensive to produce and require a significant outlay of labor in order to construct a foundation wall of conventional construction. This increases the complexity of the construction and increases the cost of the building constructed using these conventional methods. Walls constructed using these materials cannot be pre-assembled and shipped to the job site. Additionally, conventional cinder blocks or concrete walls have poor insulation characteristics and can often lead to mold and mildew problems. Furthermore, these walls often allow water and radon to freely pass through the wall.
Within the prior art, there have not been many efforts to improve upon the conventional construction techniques and create a structural foundation wall that overcomes the shortcomings of concrete walls but retains their structural strength and long-term durability. While certain attempts have been made to create facings walls, such as the assembly disclosed in U.S. Application Publication No. 2004/0182031 to Fay et al., these solutions are merely aesthetic in nature and do not provide sufficient load-bearing capacity to serve as a building foundation. The wall disclosed in Fay et al. does not have the capability to withstand both normal forces and shear forces of the magnitude encountered by a building foundation structure. Accordingly, there has been a continuing need in the art for a foundation wall system which can be produced and installed efficiently, with improved insulation characteristics, increased overall strength, and long-term durability.
One solution has been proposed in U.S. Pat. No. 7,694,481 to the present inventor. Within this patent, an engineered wall system for use in above ground or below ground applications uses structural fiberglass-reinforced plastic as an outside membrane to a frame constructed of zinc-borate treated timber strand studs and plates. Rigid foam insulation is placed in the voids between the studs and the inside wall is enclosed with conventional drywall panel. While this wall system overcomes the shortcomings of the prior art with respect to the load-bearing capacity, the open inside wall portion does not offer adequate protection against water damage occurring from inside the building structure.
An additional drawback of conventional foundation wall systems is that they lack the capability to protect the occupants and items stored within the building from bullets or shrapnel making contact with the outside wall. Because cinder blocks, fiberglass-reinforced plastic, and rigid foam insulation are generally not adequate in stopping a projectile from passing through the wall and entering the building, there is a need for a foundation wall system having bulletproof and/or shrapnel-proof characteristics.